Thaiszia - J. Bot., Košice, 22 (1): 1-31, 2012
THAISZIA
http://www.bz.upjs.sk/thaiszia
JOURNAL OF
BOTANY
Systematic significance of trichomes and foliar
epidermal morphology in the species of
Stachytarpheta Vahl. (Verbenaceae) from Nigeria
OLUBUKOLA ADEDEJI
Department of Botany, Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria;
oadedeji@oauife.edu.ng
Adedeji O. (2012): Systematic significance of trichomes and foliar
epidermal morphology in the species of Stachytarpheta Vahl.
(Verbenaceae) from Nigeria. – Thaiszia – J. Bot. 22 (1): 1-31. –
ISSN 1210-0420.
Abstract: The foliar epidermal surfaces, leaf venation and trichome
studies of different plant parts of the three species of
Stachytarpheta Vahl. family Verbenaceae found in Nigeria were
studied and compared. Observations were carried out by light
microscope. Across the genus, leaves were amphistomatic and
amphitrichomic. Qualitative foliar anatomical characters found to be
most useful in species delimitation were stomata shape, trichome
types, anticlinal cell wall pattern on adaxial surface and veinlet
termination number. Quantitative characters of taxonomic
importance, as revealed by analysis of variance (ANOVA) and
duncan multiple range test (DMRT) were length and width of
epidermal cells, stomatal index and stomatal size. Two trichome
types, glandular and non-glandular were observed in the genus.
The non-glandular trichomes were of higher numerical density on
adaxial surface than on abaxial surface. The implication of this in
terms of protection against excessive radiation, chemical control
strategies and higher temperatures was mentioned. On the abaxial
surface however, the glandular secreting trichomes were more
numerically than the non-glandular. The importance of the
preponderance of these trichomes on the abaxial surface in relation
to the role they play in the protection of essential oils earlier
reported in the family and genus, was discussed. Stomatal
abnormalities observed in the genus were, contiguous stomata
arrangement in S. cayennensis and aborted guard cells in S. indica.
Leaf venation type in the genus is pinnate craspedodromous simple
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with recurved secondary veins. Trichome distribution survey in the
different plant parts revealed specific combination types that would
be useful in species delimitation, especially in fragmentary parts
identification.
Keywords: Stachytarpheta, Verbenaceae, adaxial, abaxial, areole,
veinlet, stomata, amphitrichomic, Nigeria.
Introduction
Verbenaceae is predominantly a tropical family exhibiting a wide range of
growth habit and inhabiting diverse habitats (LILLYAMMA & SHAH 1987). The
family has about 98 genera and 3,000 species (IDU et al. 2009). They are low
shrubs, herbs or trees. Flowers are in spikes. The genus Stachytarpheta Vahl
belongs to the family Verbenaceae and is represented in West Africa and Nigeria
by three species namely Stachytarpheta cayennensis (Rich.) Vahl., S.
angustifolia (Mill.) Vahl and S. indica (L.) Vahl (HUTCHINSON & DALZIEL 1963).
They are economic plants and may be grown as ornamentals (GILL 1988).
Verbenaceae family members are popular in traditional medicine (IYANG 2003).
All the Stachytarpheta species have been used ethnomedically as anti-diabetic,
arbotifacient, emmenagogue, sedative, anti-hypertensive, anti-asthmatic and
anti-fever (SCHWONTKOWSKI 1993; BALIK 1985; DUKE & VAZQUEZ 1994). They are
also used for dysentery, as vermifuge, anti-gonorrhoea, and to cure cataract,
sore in children’s ear and also heart trouble.
Trichomes were among the first anatomical features of plants to be
recognized by early microscopists and they have played a key role in plant
taxonomy (BEHNKE 1984). Simple or non-glandular trichomes serve the plant and
humans in many ways. The morphological and mechanical features (density,
size, shape, surface texture, hair orientation) of trichomes can influence many
aspects of plant physiology and ecology (W AGNER et al. 2003). Trichomes may
serve to protect buds of some plants until defence phytochemicals are produced
(JOHNSON 1975). Thus although simple or non-glandular trichomes are not
known to accumulate post-deterrent phytochemicals, their importance to plants
and humans should not be under estimated (W AGNER et al. 2003). The
importance of non-glandular trichomes to humans is well illustrated by cotton.
The non-glandular trichomes of cotton ovules (cotton fibres, which aid seed
dispersal) are exploited more by humans than any single medicinal
phytochemical or spice (W AGNER et al. 2003). Glandular secretory trichomes, like
simple trichomes, can influence plant functions by virtue of their physical
properties (size, density). However, in addition, glandular secretory trichomes
can affect host disease and pest resistance based on phytochemicals they
secrete. The accumulation of toxic compounds at the surface allows their direct
contact with insects, pathogens and herbivores. Thus, trichome exudates are
ideally positioned to provide a first line of defence against attacking organisms,
perhaps providing time for activation of induced defences, (W AGNER et al. 2003).
The trichome types are not only useful in the identification of species, but also
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their corresponding parts, thus being important in pharmacognosy,
archaeobotany, paleobotany and agronomy (RAO & RAMAYYA 1977).
The foliar epidermis is one of the most significant taxonomic characters from
the biosystematic point of view and the taxonomic studies of a number of
families are made on the basis of leaf epidermis (BHATIA 1984; JONES 1986;
ADEDEJI 2004; ADEDEJI & JEWOOLA 2008). Although the epidermal anatomy has
been described in the leaves of a number of Verbenaceae species (PASSOS et al.
2009; METCALFE & CHALK 1950; INAMDAR 1969), surprisingly, Stachytarpheta is a
genus with paucity of anatomical research information. IDU et al. (2009), in their
work on morphological and anatomical studies of the leaf and stem of S.
jamaicensis (L. C. Rich) Schau, mentioned the presence of trichomes and
stomata on the leaf surfaces of the two species, but did not identify the types nor
give any description. One of the aims of this study is to fill this knowledge gap.
Other aims are to undertake an in-depth study of the foliar epidermis and
distribution of trichomes on plant parts in the three species of Stachytarpheta in
West Africa and Nigeria as reported by HUTCHINSON & DALZIEL (1963).
Material and methods
Leaf parts, stem, flowers were collected fresh from the three species of
Stachytarpheta, S. cayennensis (Rich.) Vahl., S.indica (Linn.) Vahl. and S.
angustifolia (Mill.) Vahl. from various locations on the campus of Obafemi
Awolowo University, Ile-Ife, Osun State, Nigeria.
For the purpose of comparative foliar anatomical work, small sizeable portions
of the leaves were cut from the median parts of mature and well expanded
leaves, that is, midway between the base and the apex, for each species studied.
The portions of the leaf blade were boiled for about 25 minutes in 90% alcohol in
the oven at about 60ºC in order to remove the chlorophyll. The leaf portions were
then washed in four to five changes of water, after which they were then boiled in
5 % sodium hydroxide solution for about 40 minutes until the materials were
decolourized. As soon as the materials became decolourized, they were washed
thoroughly in order to remove the alkaline solution. The partly cleared portions of
the leaf were finally cleared in 5 % solution of domestic bleach (parozone) for
about 30 minutes. The portions of the leaf were finally washed properly in three
to four changes of water and stored in 50 % ethanol for anatomical studies. The
cleared portions of the leaf were stained in 1 % aqueous solution of safranin O
for 3-5 minutes, washed in 3-4 changes of water to remove excess stain and
mounted in 10% glycerol solution for venation studies.
For the preparation of epidermal peels, the scrape technique of METCALFE
(1960) was used whereby the required epidermis was obtained by scraping it
from the unrequired mesophyll. Epidermal peels of both adaxial and abaxial
surfaces were made by placing the desired epidermal surfaces face down and
scraping off with a sharp blade all tissues above the desired epidermis until the
required epidermis was reached. The leaf material being scraped was
intermittently irrigated with water. The desired epidermal surface was placed on a
clean glass slide with the surface desired placed up. The epidermal peels were
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stained in 1% aqueous safranin O for 5-10 minutes and rinsed carefully in water
to remove excess stain. The peels were washed in 3-4 changes of water and
mounted in dilute glycerol solution. Stomatal size was calculated by multiplying
the length and width of the stomata. Stomatal index is the percentage proportion
of the number of stomata to the other epidermal cells present on a leaf portion.
The Stomatal Index is expressed by the formula
S x 100%
S. I. =
E+S
Where, S. I. = stomatal index, S = number of stomata per unit area,
E = number of ordinary epidermal cells plus the subsidiary cells in the same
unit area.
For the trichome studies of the different plant organs, epidermal peels and
transverse sections of different plant parts except the petals and petal tube
(which were observed directly) were made, stained with safranin O and mounted
in 70% glycerol. Photomicrographs were taken using a light microscope
equipped with an AmScope camera.
The mean, standard error and standard deviation values for the quantitative
characters were obtained using PAST Statistical Packages. The analysis of
variance (ANOVA) and duncan multiple range test (DMRT) were obtained using
SASS Package. Cluster diagrams (dendrogram) of the foliar epidermal
characters and trichomes on the adaxial and abaxial epidermal surfaces were
also prepared
Results/Observations
Epidermal surfaces
S. cayennensis (Tab. 1, Fig. 1A-D)
Epidermal cells shape is largely polygonal, regularly arranged on adaxial
surface, 50-87.5 µm long and 10-45 µm wide; polygonal irregularly arranged on
abaxial surface, 32.5-77.5 µm long and 15-37.5 µm wide. Anticlinal cell wall
straight to wavy on adaxial surface, sinuous only on abaxial surface. On both
surfaces, epidermal cells overlaying the veins are elongated and polygonal,
occasionally rectangular with straight anticlinal walls, 70-162.5 µm long and 17.537.5 µm wide on adaxial surface, 75-140 µm long and 12.5-20 µm wide on
abaxial surface. Stomata are restricted to the non-vein regions on both surfaces,
largely diacytic, often anisocytic, occasionally anomocytic on both surfaces,
circular to elliptic in shape on both surfaces, with more circular shape on adaxial
than abaxial and more elliptic on abaxial than on adaxial. Stomata size 309.38687.5 µm² on adaxial surface, 337.5-687.5 µm² on abaxial surface. Stomatal
index 14.72%-21.77% on adaxial and 26.34-36.93% on abaxial. Big rectangular,
triangular, spherical shaped crystals and small crystals in aggregates present.
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S. angustifolia (Tab. 2, Fig. 5A-F, 8D, G)
Epidermal cells shape is polygonal irregularly arranged on both adaxial and
abaxial epidermal surfaces, 55-112.5 µm long and 30-72.5 µm wide on adaxial
surface, 57.5-112.5 µm long and 25-50 µm wide on abaxial surface. Anticlinal
cell wall undulating to sinuous on adaxial surface, sinuous only on abaxial
surface. Epidermal cells overlaying the veins are elongated, polygonal to
rectangular in shape with straight anticlinal walls on both surfaces, 75-192.5 µm
long and 17.5-32.5 µm wide on adaxial surface, 90-182.5 µm long and 17.5-30
µm wide on abaxial surface. Stomata present on non-vein regions only on both
surfaces, largely diacytic, occasionally anisocytic and anomocytic on adaxial and
abaxial surfaces, elliptic in shape on both surfaces. Stomata size 525-650 µm²
on adaxial surface, 375-568.75 µm²on abaxial surface. Stomatal index is 24.7231.34% on adaxial, 28.87-33.64% on abaxial surface. Spherical to rectangular
shaped crystals and groups of small crystals present.
S. indica (Tab. 3, Figs. 9A-E, I, 11F)
Epidermal cells shape polygonal, irregularly arranged on both surfaces, 65137.5 µm long and 25-60 µm wide on adaxial surface, 55-127.5 µm long and
27.5-67.5 µm wide on abaxial surface. Anticlinal cell wall undulating to sinuous
on adaxial surface, sinuous only on abaxial surface. On both surfaces, epidermal
cells overlaying the veins are elongated, polygonal on adaxial surface, polygonal
to rectangular on abaxial surface, anticlinal wall straight on both surfaces 77.5175 µm long and 22.5-35 µm wide on adaxial surface, 75-140 µm long and 12.520 µm wide on abaxial surface. Stomata found on non-vein regions only, largely
elliptic in shape on both surfaces. Stomata size 568.75-987.5 µm² on adaxial
surface, 407.5-937.5 µm² on abaxial surface. Stomatal index is 10.71-19.40% on
adaxial surface, 22.73-30.43% on abaxial surface.
Trichome studies
S. cayennensis (Tabs. 1, 7-8, Figs. 2A-G, 3A-D, 4A-G)
Epidermal surfaces:
Adaxial:
Non-glandular: spine-like, unicellular, bicellular, multicellular
Glandular: 1, 2, 4, 5-9 cells secrotory head, short stalk 2 celled secretory head.
Abaxial:
Non-glandular: spine-like, unicellular. bicellular, multicellular
Glandular: 1, 2, 4, 5-9 cells secretory head.
Midrib:
Non-glandular: bicellular, multicellular
Glandular: absent
Petiole:
Non-glandular: bicellular, multicellular
Glandular: 2 cells secretory head, short stalk, 4 cells secretory head.
Stem:
Non-glandular: bicellular, multicellular
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Glandular: 2 cells secretory head.
Petals:
Non-glandular: unicellular
Glandular: short stalked 1-5 cells secretory head
Petal tube:
Non-glandular: absent
Glandular: long stalked 1-4 cells secretory head.
Calyx:
Non-glandular: spine-like, multicellular
Glandular: 2 cells secretory head
Veins:
Non-glandular: spine-like, unicellular, bicellular
Glandular: 2 cells secretory heads
S. angustifolia (Tabs. 2, 7-8, Figs. 5E, H-I, 6A-H, 7A-I, 8A-B, E).
Epidermal surfaces:
Adaxial:
Non-glandular: bicellular
Glandular: 1, 3, 4, 5-9, 10-16 - celled secretory head.
Abaxial:
Non-glandular: bicellular, multicellular
Glandular: 1, 3, 4, 5-9, 10-16 cells secretory head
Midrib:
Non-glandular: bicellular, multicellular
Glandular: 3, 4, 5-9 cells secretory head.
Petiole:
Non-glandular: unicellular, bicellular, multicellular
Glandular: 4 cells secretory head
Stem:
Non-glandular: spine-like, multicellular
Glandular: 2, 5-9 cells secretory head
Petals:
Non-glandular: unicellular
Glandular: 1 cell secretory head, short stalk 1-6 cells secretory head.
Petal tube:
Non-glandular: absent
Glandular: long stalk 1-2 cells secretory head
Calyx:
Non-glandular: spine-like, unicellular, bicellular
Glandular: 3-4 cells secretory head.
Veins:
Non-glandular: spine-like, unicellular, bicellular, multicellular
Glandular: 2, 4, 5-9 cells secretory head.
S. indica (Tabs. 3, 7-8, Figs. 9F-G, 10A-G, 11A-E, G-I)
Epidermal surfaces:
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Adaxial:
Non-glandular: spine-like, unicellular
Glandular: 1, 2, 3 cells secretory head.
Abaxial:
Non-glandular: unicellular
Glandular: 1, 2, 3 cells secretory head
Midrib:
Non-glandular: bicellular, multicellular
Glandular: 2 cells secretory head.
Petiole:
Non-glandular: bicellular, multicellular
Glandular: 2 cells secretory head, short stalk 1-2 cells secretory head
Stem:
Non-glandular: unicellular, multicellular
Glandular: 1-2 cells secretory head.
Petals:
Non-glandular: unicellular
Glandular: short stalk 1-7 cells secretory head
Petal tube:
Non-glandular: absent
Glandular: short stalk, 1-2 cells secretory head, long stalk 1 cell secretory head.
Calyx:
Non-glandular: spine-like
Glandular: 1-2 cells secretory head.
Veins:
Non-glandular: spine-like, bicellular, multicellular
Glandular: 2 cells secretory head.
Leaf Venation Studies
S. cayennensis (Tab. 6, Fig. 9H)
Venation type is pinnate craspedodromous simple, secondary veins recurved.
Areole shape is polygonal, occasionally rectangular 260-450 µm long and 200430 µm wide. Veinlet termination 0-2 per areole, simple to branched.
S. angustifolia (Tab. 6, Fig. 5G)
Venation type is pinnate craspedodromous simple with recurved veins. Areole
shape largely polygonal, occasionally triangular or rectangular, 230-700 µm long
and 180-410 µm wide. Veinlet termination 0-4 per areole, largely branched.
S.indica (Tab. 6, Fig. 9H)
Venation type is pinnate craspedodromous simple, secondary veins recurved.
Areole shape largely polygonal, occasionally rectangular, 310-830 µm long and
200-310 µm wide. Many areoles without any veinlet termination observed, 1-2
per areole when they occur, simple to branched.
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Trichome Density on the foliar epidermal surfaces
S. cayennensis (Tab. 7):
Adaxial surface: Non-glandular 5-10; Glandular 0-3
Abaxial surface: Non-glandular 0-3; Glandular 1-6
S. angustifolia (Tab. 7):
Adaxial surface: Non-glandular 0-1; Glandular 4-17
Abaxial surface: Non-glandular 0-1; Glandular 6-18
S. indica (Tab. 7):
Adaxial surface: Non-glandular 0-1; Glandular 0-1
Abaxial surface: Non-glandular 0-1; Glandular 1-2.
Statistical Analysis
Tables 1-3 present the Simple Descriptive Statistics of the quantitative
characters of foliar epidermal surfaces of the three Stachytarpheta species.
analysis of variance (ANOVA) for epidermal cell length, epidermal cell breadth,
stomatal size, stomata index, vein cell length and vein cell breadth revealed
significant differences at Pr.
0.0001 for all characters on both adaxial and
abaxial epidermal surfaces except for vein cell length and breadth on adaxial
surface which showed no significant difference. Duncan multiple range test
(DMRT) showed interesting species groupings based on these characters (Tab.
4). The dendrogram from the Cluster Analysis based on quantitative data also
show species relationships (Figs. 12-13).
Discussion
The present investigation represents the first detailed qualitative and
quantitative study of leaf epidermis, leaf venation and trichome studies in the
genus Stachytarpheta in Nigeria. The three species reported in Nigeria and West
Africa, S. cayennensis, S. angustifolia, S. indica, are included in the study.
The foliar epidermis is one of the most significant taxonomic characters from
the biosystematic point of view and the taxonomic studies of a number of
families and genera have been made on the basis of leaf epidermis (BHATIA
1984; JONES 1986; ADEDEJI 2004; ADEDEJI et al 2007; ADEDEJI & JEWOOLA
2008). SCOTLAND et al. (2003) is of the opinion that rigorous and critical
anatomical studies of fewer morphological characters in the context of molecular
phylogenies is fruitful to integrate the strength of morphological data with those of
sequence data (HAYAT et al. 2009)
Leaves are amphistomatic and amphitrichomic in the three species. Epidermal
cells on adaxial surface are generally polygonal in shape, regularly arranged in S.
cayennensis, sinuous, irregularly arranged in the other two species. Anticlinal cell
walls on adaxial surface are undulating to sinuous in S. angustifolia and S. indica
but straight to wavy in S. cayennensis. This delimits S. cayennensis from the
other two species. On the abaxial epidermal surface however, the epidermal cell
8
shape is polygonal, irregularly arranged with sinuous anticlinal walls in the three
species. The sinuosity of the epidermis cells appears to be fixed genetically.
SHAHEEN et al. (2010) delimited Althaea and Alcea, the two closely related
genera in the family Malvaceae using anatomical sizes of the epidermal cells. In
this study, length and width of the epidermal cells is of taxonomic significance
and can be helpful in delimiting the three species of Stachytarpheta as indicated
by the species grouping from Duncan Multiple Range Test (Tab. 4). It is longest
in S. indica on both adaxial and abaxial surfaces while it is widest in S.
angustifolia on the adaxial surface and widest in S. indica on abaxial surface.
Epidermal cells overlaying the veins on both adaxial and abaxial epidermal
surfaces are largely polygonal with straight anticlinal walls. From the ANOVA
Test for significance and Duncan Multiple range Test, the cells are not
significantly different in length and breadth on the adaxial epidermal surfaces of
the three species but are significantly different on the abaxial surface, cell
breadth can therefore be used for delimiting the species. According to DILCHER
(1974), stomata are ecologically less variable characters. Stomata in the genus
are largely diacytic, occasionally anisocytic and anomocytic. No clear cut
delimitation of any taxa can be made based on stomatal type, hence the
character is not of taxonomic importance in the genus.
METCALFE & CHALK (1950), in their summary on family Verbenaceae reported
that stomata on the adaxial surface of a few species of the genus Stachytarpheta
are arranged in groups. INAMDAR (1969) reported contiguous stomata, stomata
with a single guard cell, and aborted guard cells as abnormalities in the family
Verbenaceae. Two out of the three mentioned abnormalities occur in this genus.
They are stomata arrangement in groups (contiguous) in the upper or adaxial
surface of S. cayennensis and aborted guard cells occurring in S. indica. In the
three species studied, the stomatal index was higher on the abaxial surface than
on the adaxial surface. This seems to be a preventive mechanism against photoinhibition, since the adaxial surface is more exposed to solar radiation as most of
the leaves are in horizontal position (SMITH et al. 1998). The size and shape of
stomata are important characters taxonomically (THAIR & RAJPUT 2009).
Stomatal index and size, though quantitative are of taxonomic importance in the
genus Stachytarpheta as observed in this study. The analysis of variance
(ANOVA) Test for significance, revealed a significant difference among species
in the two characters, while the duncan multiple range test revealed delimitation
at species level. S. indica has the biggest stomatal size on both adaxial and
abaxial epidermal surfaces with a corresponding lower stomatal index on both
surfaces. Stomatal shape is largely circular to elliptic in S. cayennensis but
elliptic largely in S. angustifolia and S. indica.
Venation type in the genus is pinnate craspedodromous simple with recurved
secondary veins. The areole shape are generally polygonal in all 3 species,
occasionally rectangular or triangular. Areole length is longest in S. indica and
shortest in S. cayennensis (Tab. 6), while it is widest in S. cayennensis and
narrowest in S. indica. Veinlet termination number per areole ranged from 0-2 in
S. cayennensis, often 0, occasionally 1-2 in S. indica, 0-4 in S. angustifolia,
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simple to branched in the 3 species with S. angustifolia having more branched
veinlet termination in the areoles than S. indica and S. cayennensis. OGUNDIPE &
W UJEK (2004) reported veinlet termination number to be one of the most useful
anatomical characters in the family Bignoniaceae.
A study of the trichome types in the different organs show that both glandular
and non-glandular trichome types can be found in the genus and their
organographic distribution within each species vary. ADEDEJI et al. 2007,
reported the importance of trichome distribution types in the different organs of
the plant body in the delimitation of genera and species within the family
Solanaceae. RAMMAYA & RAO (1976), RAO & RAMMAYA (1977), YAN-MING & RUW EN (1993), CELKA et al. (2006), ADEDEJI (2007), have all emphasized the
taxonomic implication of trichomes. The glandular and non-glandular trichomes
observed in the Stachytarpheta species, are distributed widely in the
Verbenaceae family (SOLEREDER 1908; METCALFE & CHALK 1950). It must
however be noted that trichome distribution in the genus is not abundant, they
are present but often sparsely distributed. The micro morphological
characteristics of foliar trichomes have played an important role in plant
systematics, especially of particular groups at generic and specific levels
(HARDIN 1979). Such type of studies on the field has fascinated plant
morphologists and systematists towards the diversity of trichome features (YANMING & RU-W EN 1993).
On the foliar epidermal surfaces, non-glandular trichome is of higher
frequency on adaxial surface than on abaxial surface, occurring largely in S.
cayennensis than in S.angustifolia and S. indica. The largest frequency of these
trichomes in the adaxial surface of S. cayennensis can be related to protection
against excessive radiation and higher temperatures, as reported in the literature
(FRANCINO 2006; VALKAMA 2003; PASSOS et al. 2009). However in most cases,
the true ecological function of the trichomes has not been supported by
experimental data (W ERKER 2000). The penetration of herbicides in the plant
tissues is essential for the effective chemical control of weed (PROCOPIO 2003).
The anatomical characteristics practically determine the ease with which these
products can be absorbed (HESS & FALK 1990). Trichomes in the leaf surface
can intercept pulverized drops, preventing these from reaching the epidermis.
Thus the high frequency of non-glandular trichomes in the adaxial surface of S.
cayennensis would be advantageous for the species when undergoing chemical
control strategies. Chemical control would be prone to negatively affect S.
angustifolia and S. indica with low frequency of non-glandular trichomes in the
adaxial surface (Tab. 7), rendering the epidermal cells more exposed to the
agrochemical action. S. angustifolia is unique in being the only species without
the spine-like non-glandular trichomes on both adaxial and abaxial epidermal
surfaces.
The different types of glandular trichomes on the foliar epidermal surfaces
described for the three species of Stachytarpheta are important distinctive
characteristics. The Verbenaceae family stands out for presenting different types
of glandular trichomes (PASSOS et al. 2009). PASSOS et al. (2009) reported that
10
the occurrence of glandular trichomes can be considered an important distinctive
characteristic for L. camara and L. radula (family Verbenaceae) they studied.
Trichomes, particularly the secretory ones are considered important tools for
taxonomy (SOLEREDER 1908; METCALFE & CHALK 1950; FAHN 1979; THEOBALD et
al. 1979). The three species of Stachytarpheta studied can be delimited on the
basis of the glandular trichome type on the epidermal surfaces. The 4 cells
secretory head glandular trichome type was observed to be the major glandular
type in S. angustifolia while the 2 cells type was predominant on the foliar
epidermal surfaces of S. indica. S. angustifolia can also be delimited from the
other two species because of the presence of 10-16 cells secretory head
glandular trichome which is absent in the other two species. S. cayennensis can
also be delimited from S. indica by the presence of 4, 5-9 cells secretory head
glandular trichome. The glandular trichomes in the three species are more
abundant in the abaxial surface than in the adaxial (Tab. 7). This tallies with the
observation of PASSOS et al. (2009), in their studies on the genus Lantana.
Aromatic plants grow in sunny environments and the trichomes, being protected
in the abaxial surface, allow the secretions to remain for an extended time in the
plant.. SOLEREDER (1908), RAGHAVAN & ARORA (1960), INAMDAR (1969),
THEOBALD et al. (1979), SINHA & SHARMA (1984), GOTTLIEB & SALATINO (1987),
RUEDA (1993), JUDD et al. (1999) have reported the presence of glandular
trichomes secreting essential oils in the Verbenaceae. These oils normally
evaporates and are released under high temperature and low humidity, hence
their preponderance on the abaxial surface is largely for protection. Moreover,
the sites of accumulation have an important influence on the effectiveness of
anti-herbivory substance (GERSHENZON & CROTEAU 1991). S. angustifolia is the
species with the highest frequency of glandular trichomes, occurring more on the
abaxial surface. This is quite diagnostic for this species, suggesting its ability for
secretion of these essential oils more than in the other two species. The
glandular trichomes also present ecological significance, being associated with
the plant interaction with the environment, interfering efficiently against the attack
of herbivores and pathogens (LEVIN 1973; JOHNSON 1975; RODRIGUEZ et al.
1984; JUNIPER & SOUTHWOOD 1986; MARQUIS 1992). Evidence from wild and
cultivated species gives support to this ecological role (DUFFEY 1986; JEFFREE
1986; DAVID & EASWARAMOORTHY 1988; W OODMAN & FERNANDES 1991;
BERNAYS & CHAPMAN 1994; PETER et al. 1995; ROMEIS et al. 1999).
A trichome distribution survey of the other plant parts, (Tab. 8) revealed
specific combination types that can be used for species delimitation. The
bicellular and multicellular non-glandular trichome types can be found on the
midrib of the three species while S. indica can be delimited from the other two
species by the presence of the 2 cells secretory head glandular trichome which is
absent in the other two species. S. angustifolia is also unique in possessing the
3, 4, and 5-9 cells secretory head glandular tichome absent in the other two
species. Trichome types in the petiole of S. indica and S. cayennensis are the
same, bicellular and multicellular non-glandular, 2 cells secretory head and short
stalked secretory head glandular trichomes, while S. angustifolia differs from the
11
others in having the unicellular non-glandular and the 4 cells secretory head
glandular trichome. On the stem, trichome types multicellular non-glandular and
2 cells secretory head glandular tichomes are observed in the three species
while each has specific trichome types delimiting it. Unicellular non-glandular
trichome and short stalked secretory head glandular trichome are both present
on the petals of the three species with S. angustifolia having an additional 1 cell
secretory head glandular trichome type. The long stalked secretory head
glandular trichome type is unique to the petal tube and observed in the three
species. Spine-like non-glandular trichome was observed on the calyx of the
three species while each has additional types diagnostic for it. The veins also
revealed specific trichome combination types unique for each species. The
specific organographic trichome combination types in each species would be
useful in fragmentary parts identification.
Crystals in the form of small needles or prisms are widely distributed in the
parenchymatous tissues of both leaf axis, of the family Verbenaceae (METCALFE
& CHALK 1950). In this study, crystals of different sizes and shapes were
observed in the various plant parts in the three species of Stachytarpheta,
occurring singly when big, and in groups when small.
Cluster diagrams (Figs. 12-13) show the relationship or closeness of the three
species to one another based on the trichomes and epidermal surfaces
quantitative characters. Based on the adaxial surface characters, S. angustifolia
and S. indica are closer while S. cayennensis separates out. Dendrogram of the
abaxial characters reveals a closer similarity between S. cayennensis and S.
angustifolia. This confirms the report of ADEDEJI (2010) who worked on the
palynology of the genus, that S. cayennensis and S. angustifolia are the closest
with S. indica closer to S. angustifolia and farther from S. cayennensis
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Legend to Tables 1-3
X1
X2
X3
X4
X5
X6
X7
X8
X9
X10
X11
X12
X13
X14
X15
X16
X17
X18
X19
X20
X21
X22
X23
X24
X25
X26
Epidermal cell length (µm)
Epidermal cell breadth (µm)
Stomata size (µm²)
Stomatal index (%)
Vein cell length (µm)
Vein cell breadth (µm)
Spine-like non-glandular trichome length (µm)
Spine-like non-glandular trichome breadth (µm)
Unicellular non-glandulartrichome length (µm)
Unicellular non-glandular trichome breadth (µm)
Bicellular non-glandular trichome length (µm)
Bicellular non-glandular trichome breadth (µm)
Multicellular non-glandular trichome length (µm)
Multicellular non-glandular trichome breadth (µm)
1 cell (unicellular) secretory head glandular trichome length (µm)
1 cell (unicellular) secretory head glandular trichome breadth (µm)
2 cells (bicellular) secretory head glandular trichome length (µm)
2 cells (bicellular) secretory head glandular trichome breadth (µm)
3 cells (tricellular) secretory head glandular trichome length (µm)
3 cells (tricellular) secretory head glandular trichome breadth (µm)
4 cells (multicellular) secretory head glandular trichome length (µm)
4 cells (multicellular) secretory head glandular trichome breadth (µm)
5-9 cells (multicellular) secretory head glandular trichome length (µm)
5-9 cells (multicellular) secretory head glandular trichome breadth (µm)
10-16 cells (multicellular) secretory head glandular trichome length (µm)
10-16 cells (multicellular) secretory head glandular trichome breadth (µm).
15
Tab. 1. Simple descriptive statistics of the quantitative characters of foliar
epidermal surfaces of S. cayennensis.
Variation
X1
X2
X3
X4
X5
X6
X7
X8
X9
X10
X11
X12
X13
X14
X15
X16
X17
X18
X19
X20
X21
X22
X23
X24
X25
X26
Minimum
Ad
Ab
50.00 32.50
10.00 15.00
309.38 306.25
14.72 26.34
70.00 75.00
17.50 12.50
20.00 19.00
10.00
9.00
35.00 33.00
15.00 13.00
90.00 200.00
17.50 19.00
187.50 187.50
30.00 22.50
20.00 20.00
15.00 19.00
25.00 27.50
17.50 22.50
0
0
0
0
27.50 27.50
27.50 24.00
28.00 30.00
26.00 27.50
0
0
0
0
Maximum
Ad
Ab
87.50 77.50
45.00 37.50
687.50 687.50
21.77 36.93
162.50 140.00
37.50 20.00
30.00 28.00
17.50 18.00
65.00 60.00
25.00 23.00
135.00 240.00
37.50 25.00
452.50 252.50
52.50 25.00
32.50 31.00
25.00 25.00
27.50 32.00
22.50 26.00
0
0
0
0
36.00 35.00
30.00 28.00
36.00 35.00
28.00 30.00
0
0
0
0
Mean
Standard deviation Standard error
Ad
Ab
Ad
Ab
Ad
Ab
66.40 55.20
11.34
10.82
2.27
2.16
27.70 25.90
7.84
5.44
1.57
1.08
483.24 489.75 101.34 112.59 20.27 22.52
17.98 31.72
1.91
2.80
0.38
0.56
116.60 112.30
29.96
19.87
5.99
3.97
26.00 17.60
5.99
2.55
1.99
0.51
27.00 26.00
4.47
3.90
2.00
1.90
14.00 13.80
2.85
2.05
1.27
1.15
51.50 49.50
13.87
12.00
6.20
5.80
20.00 19.00
3.95
3.00
1.77
1.46
122.00 219.00
18.57
14.32
8.31
6.40
31.40 21.80
8.32
2.59
3.72
1.16
309.00 215.50 129.98
33.88 58.13 15.15
38.50 23.60
9.78
1.29
4.37
0.58
24.50 26.80
5.42
4.44
2.42
1.98
19.50 21.20
3.70
2.39
1.66
1.07
27.00 29.30
1.12
1.96
0.50
0.87
20.00 24.10
1.77
1.43
0.79
0.64
0
0
0
0
0
0
0
0
0
0
0
0
32.00 30.50
4.17
3.32
1.86
1.48
28.40 26.50
1.08
1.87
0.48
0.84
31.80 32.00
3.49
2.12
1.56
0.95
27.00 28.70
0.71
0.97
0.32
0.44
0
0
0
0
0
0
0
0
0
0
0
0
Key: Ad - Adaxial, Ab - Abaxial
Tab. 2. Simple descriptive statistics of the quantitative characters of foliar
epidermal surfaces of S. angustifolia.
Variation
X1
X2
X3
X4
X5
X6
X7
X8
X9
X10
X11
X12
X13
X14
X15
X16
X17
X18
X19
X20
X21
X22
X23
X24
X25
X26
Minimum
Ad
Ab
55.00 57.50
30.00 25.00
525.00 375.00
24.72 28.87
75.00 90.00
17.50 17.50
0
0
0
0
0
0
0
0
220.00 235.0
28.00 27.00
0
237.50
0
32.50
35.00 35.00
35.00 35.00
0
0
0
0
27.50 34.00
27.00 27.50
32.50 32.50
32.50 35.00
30.00 35.00
28.00 37.50
50.00 50.00
47.50 50.00
Maximum
Mean
Standard Deviation Standard Error
Ad
Ab
Ad
Ab
Ad
Ab
Ad
Ab
112.50 112.50 88.44 88.10
16.67
14.90
3.33
2.98
72.50 50.00 50.70 36.50
13.43
5.91
2.69
1.18
650.00 568.75 614.23 505.25
49.12
56.12
9.82
11.23
31.34 33.64 28.88 31.14
1.80
1.31
0.36
0.26
192.50 182.50 130.30 126.80
34.22
28.17
6.84
5.63
32.50 30.00 26.10 23.50
3.54
2.80
0.71
0.56
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
232.00 245.00 227.90 241.40
4.69
4.16
2.10
1.86
32.00 29.00 29.60 27.90
1.52
0.74
0.68
0.33
0
495.00
0
325.50
0
101.62
0
45.44
0
55.00
0
48.50
0
9.29
0
4.15
38.00 37.50 36.10 36.00
1.52
1.37
0.68
0.61
40.00 40.00 37.20 38.00
1.89
2.09
0.85
0.93
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
33.00 40.00 30.40 36.90
2.33
2.41
1.04
1.08
29.00 40.00 27.80 33.90
0.76
5.92
0.34
2.65
40.00 43.00 36.50 36.60
2.85
3.99
1.27
1.78
42.50 41.00 35.00 38.30
4.33
2.33
1.94
1.04
33.00 41.00 32.00 38.40
1.17
2.30
0.52
1.03
30.00 40.00 29.00 38.70
1.00
0.97
0.45
0.44
59.00 59.00 55.90 54.80
3.61
3.27
1.62
1.46
55.00 56.00 52.00 53.00
3.26
2.24
1.46
1.00
Key: Ad - Adaxial, Ab - Abaxial
16
Tab. 3. Simple descriptive statistics of the quantitative characters of foliar
epidermal surfaces of S. indica.
Variation
X1
X2
X3
X4
X5
X6
X7
X8
X9
X10
X11
X12
X13
X14
X15
X16
X17
X18
X19
X20
X21
X22
X23
X24
X25
X26
Minimum
Maximum
Mean
Standard deviation Standard error
Ad
Ab
Ad
Ab
Ad
Ab
Ad
Ab
Ad
Ab
65.00 55.00 137.50 155.00 104.70 103.90
18.85
20.99
3.77 4.20
25.00 27.50 60.00 67.50 38.70 39.80
7.22
8.84
1.44 1.77
568.75 407.50 987.50 937.50 771.44 710.75 122.35 127.79 24.47 25.56
10.71 22.73 19.40 30.43 15.93 26.93
2.80
2.01
0.56 0.40
77.50 100.00 175.00 210.00 134.00 165.50
29.32
34.47
5.86 6.89
22.50 20.00 35.00 37.50 26.80 25.40
3.50
3.66
0.70 0.73
20.00
0
30.00
0
23.00
0
4.47
0
2.00 0
12.00
0
15.00
0
13.40
0
1.47
0
0.66 0
27.50 27.50 62.00 32.00 47.30 29.10
15.11
1.88
6.76 0.84
15.00
9.00 25.00 11.00 21.00 10.00
3.81
0.71
1.70 0.32
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
35.00 33.50 42.00 42.50 39.60 37.40
2.70
4.46
1.21 2.00
37.00 22.00 40.00 28.00 39.20 24.00
1.30
2.55
0.58 1.14
35.00 33.00 42.50 42.50 38.00 37.60
4.11
4.55
1.84 2.03
25.00 22.00 30.00 30.00 26.50 25.80
2.24
3.19
1.00 1.43
35.00 33.00 43.00 45.00 39.60 37.80
4.20
5.36
1.88 2.40
25.00 28.00 30.00 30.00 27.50 29.60
1.80
0.89
0.81 0.40
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Key: Ad - Adaxial, Ab - Abaxial
Tab. 4. Species grouping from Duncan’s Multiple Range Test (Means with the same
letter are not significantly different)
Character
Epidermal cell length (µm)
Epidermal cell breadth (µm)
Stomatal size (µm²)
Stomatal Index (%)
Vein cell length (µm)
Vein cell breadth
Species name
S. indica
S. angustifolia
S. cayennensis
S. indica
S. angustifolia
S. cayennensis
S. indica
S. angustifolia
S. cayennensis
S. indica
S. angustifolia
S. cayennensis
S. indica
S. angustifolia
S. cayennensis
S. indica
S. angustifolia
S. cayennensis
17
Grouping
Adaxial
104.70 A
88.44 B
66.40 C
50.70 A
38.70 B
27.70 C
771.44 A
614.23 B
483.24 C
28.88 A
17.98 B
15.93 C
134.00 A
130.30 A
116.60 A
26.80 A
26.10 A
26.00 A
Abaxial
103.90 A
88.10 B
55.20 C
36.50 A
39.80 A
25.90 B
710.75 A
505.25 B
489.75 B
31.14 A
31.72 A
26.73 B
165.50 A
126.80 B
112.30 B
25.40 A
23.50 B
17.60 C
Tab. 5: Summary of the qualitative foliar epidermal characters
Species
Epidermal cells
shape
Adaxial
Abaxial
S. cayennensis Polygonal Polygonal
Regularly Irregularly
arranged arranged
S. angustifolia Polygonal Polygonal
Irregularly Irregularly
arranged arranged
Polygonal Polygonal
S. indica
Irregularly Irregularly
arranged arranged
Anticlinal cell wall
Epidermal cells
overlaying veins
Adaxial
Abaxial Adaxial
Abaxial
Straight to Sinuous Polygonal Polygonal
wavy
Stomatal type
Adaxial
Diacytic
Anisocytic
Anomocytic
Undulating Sinuous Polygonal to Polygonal to Diacytic
to sinuous
rectangular rectangular Anisocytic
Anomocytic
Undulating Sinuous Polygonal Polygonal to Diacytic
to sinuous
rectangular Anisocytic
Anomocytic
Stomatal shape
Abaxial
Diacytic
Anisocytic
Anomocytic
Diacytic
Anisocytic
Anomocytic
Diacytic
Anisocytic
Anomocytic
Crystals
Adaxial Abaxial Adaxial Abaxial
Circular Elliptic to +
+
to elliptic circular
Elliptic
Elliptic
+
+
Elliptic
Elliptic
+
+
Key: + present
18
Tab. 6: Leaf venation studies; minimum (mean ± standard error) maximum.
Characters
Venation type:
Primary veins
Secondary veins
Areoles:
Areole shape
Areole Length (µm)
Areole Width (µm)
Veinlet termination:
Number per areole
Description
S. cayennensis
S. angustifolia
S. indica
Pinnate craspedodromous simple
Recurved
Pinnate craspedodromous simple
Recurved
Pinnate craspedodromous simple
Recurved
Polygonal, occasionally rectangular
260(372±33.38)450
200(314±40.69)430
Polygonal, occasionally triangular or rectangular
230(502±76.90)700
180(310±48.89)410
Polygonal, occasionally rectangular.
310(572±91.24)830
200(244±20.15)310
0-2
Simple to branched
0–4
Often branched
0ften 0, occasionally 1 – 2.
Simple to branched
Tab. 7: Trichome density on the foliar epidermal surfaces of the Stachytarpheta species.
Trichome type
Non-glandular
Glandular
Species
S. cayennensis
S. angustifolia
S. indica
S. cayennensis
S. angustifolia
S. indica
Ad
5
0
0
0
4
0
Minimum
Ab
0
0
0
1
6
1
Ad
10
1
1
3
17
1
Maximum
Ab
3
1
1
6
18
2
Ad
7.2
0.2
0.6
1.6
8.6
0.4
Mean
Ab
0.6
0.2
0.2
4.2
10.2
1.4
Standard deviation
Ad
Ab
1.92
1.34
0.45
0.45
0.55
0.40
1.34
3.11
5.18
2.97
0.55
0.55
Standard Error
Ad
Ab
0.86
0.60
0.20
0.20
0.24
0.20
0.60
1.39
2.32
1.33
0.24
0.24
Key: Ad - Adaxial, Ab - Abaxial
Tab. 8: Distribution of trichomes on the different organs of the Stachytarpheta species
Species
19
Adaxial epidermal
surface
S. cayennensis A, B, C, D, E, F, H, K*
S. angustifolia C, E, G, H, I, J
A, E, F, G
S. indica
Key:
A
B
C
D
E
F
G
H
I
J
K
L
Abaxial epidermal
surface
A, B, C, D, E, F, H, I
D, H, I
E, F, G
Midrib
Petals Petal
tube
C, D
C, D, F, K C, D, F.
B, K
L
C, D, G, H, I B, C, D, H A, D, F, I B, E, K L
C, D, F
C, D, F, K B, D, E, F B, K
K, L
Spine-like non-glandular trichome
Unicellular non-glandular trichome
Bicellular non-glandular trichome
Multicellular non-glandular trichome
1 cells (unicellular) secretory head glandular trichome
2 cells (bicellular) secretory head glandular trichome
3 cells (tricellular) secretory head glandular trichome
4 cells (multicellular) secretory head glandular trichome
5-9 cells (multicellular) secretory head glandular trichome
10-16 cells (multicellular) secretory head glandular trichome
Short stalk secretory head glandular trichome
Long stalk secretory head glandular trichome.
Petiole
Stem
Calyx
Veins
A, D, F.
A, B, C, D, F.
A, B, C, G, H A, B, C, D, F, H, I
A, E, F
A, C, D, F
A
B
C
D
Fig. 1. S. cayennensis (A-D, X400): A. Adaxial epidermal surface (arrow indicates
anisocytic stomatal type); B. Abaxial epidermal surface (arrow indicates diacytic
stomata, double arrow indicates anomocytic stomatal type); C. Adaxial epidermal
surface (arrow indicates anomocytic stomatal type); D. Adaxial epidermal surface
showing contiguous stomata.
20
A
B
C
F
D
E
G
Fig. 2. S. cayennensis (A-C, E-G X400; D, X100): A. Spine-like non-glandular
trichome; B. Bicellular non-glandular trichome on petiole; C. Bicellular nonglandular trichome on adaxial epidermal surface; D. Tricellular (Multicellular) nonglandular trichomes on the midrib; E. Multicellular non-glandular trichome with the
basal cell shrivelled on petiole and stem; F. Multicellular non-glandular trichome
on stem and veins; G. Multicellular non-glandular trichome on calyx.
21
A
B
C
E
D
F
G
Fig. 3. S. cayennensis (A-G, X400): A. cells secretory head glandular trichome on
adaxial epidermal surface; B. 2 cells secretory head glandular trichome on abaxial
epidermal surface; C. short stalk secretory head glandular trichome on adaxial
epidermal surface (arrow indicates short stalk); D. short stalk, 4 cells secretory
head glandular trichome on petiole and petal; E. Oblong crystals on petals and
epidermal surfaces;F. Spherical crystals on petals and epidermal surfaces; G.
Rectangular crystals on petals and epidermal surfaces.
22
B
A
E
C
D
F
G
Fig. 4. S. cayennensis (A-G, X400): A. Unicellular non-glandular trichome on petal;
B., D., G. Short stalk, 2 cells secretory head glandular trichome on petal; C. Short
stalk (with arrow), 5 cells secretory head glandular trichome on petal; E. Bicellular
non-glandular trichome on petal; F. Short stalk, 4 cells secretory head glandular
trichome on petal.
23
A
C
B
D
E
F
G
H
I
Fig. 5. S. angustifolia (A-F, H-I, X400; G, X100): A. Adaxial epidermal surface (arrow
indicates diacytic stomata, double arrow, anisocytic stomata); B. Abaxial
epidermal surface (arrow indicates diacytic stomatal type, double arrow anisocytic
stomata type); C.-D. Anomocytic stomatal type on abaxial epidermal surface; E.
Trichome base on abaxial epidermal surface (with the base of a trichome); F. Vein
cells on abaxial surface; G. Venation pattern (arrow indicates branched veinlet
termination); H. Unicellular non-glandular trichome on adaxial epidermal surface; I.
Bicellular non-glandular trichome on adaxial epidermal surface.
24
A
B
C
D
F
E
G
H
Fig. 6. S. angustifolia (A-H, X400): A. Tricellular (multicellular) non-glandular
trichome on midrib; B. Multicellular non-glandular trichomes on midrib and stem;
C. 1 cell secretory head glandular trichome on epidermal surfaces; D. 3 cells
secretory head glandular trichome on epidermal surfaces, midrib and calyx; E. 4
cells secretory head glandular trichome on epidermal surfaces, midrib, petiole,
calyx and vein; F. 6 cells secretory head glandular trichome on epidermal surfaces;
G. 8 cells secretory glandular trichome on epidermal surfaces; H. 16 cells
secretory head glandular trichome on epidermal surfaces.
25
A
B
D
G
C
E
F
H
I
Fig. 7. S. angustifolia (A-I, X400): A. 1 cell secretory head glandular trichome on
petals; B.-C. Short stalk (faint, with arrow) 8 cells secretory head glandular
trichome on petals; D. Short stalk (faint, with arrow) 5 cells secretory head
glandular trichome on petals; E. Short stalk, 1 cell secretory head glandular
trichome on petals; F. Short stalk, 2 cells secretory head glandular trichome on
petals; G. Short stalk, 3 cells secretory head glandular trichome on petals; H. Short
stalk (hooked), 5 cells secretory head glandular trichome on petals; I. Unicellular,
non-glandular trichome on petals.
26
B
A
C
E
D
F
G
Fig. 8. S. angustifolia (A.-G., X400): A. Long stalk, 1-2 cells secretory head
glandular trichome on petal tube; B. Short stalk 2-6 cells secretory head glandular
trichome on petals; C. Groups of small crystals on petal tube (arrow indicates
crystals); D. Groups of small crystals on epidermal surfaces (arrows indicate
crystals); E. Crystals on petal with short stalk, 2 cells secretory head glandular
trichome; F. Spherical crystal on stem and epidermal surfaces; G. Rectangular
crystal on epidermal surfaces.
27
A
B
C
D
F
E
G
H
I
Fig. 9. S. indica (A-G, I, X400; H, X100): A. Adaxial epidermal surface (arrow
indicates diacytic stomatal type); B. Abaxial epidermal surface (arrow indicates
aborted guard cell); C. Abaxial epidermal surface with anisocytic (with arrow)
stomatal type on abaxial surface; D. Abaxial epidermal surface with diacytic (with
arrow) and anisocytic (double arrow) stomatal types; E. Abaxial epidermal surface
with normal snd aborted guard cells; F. Adaxial epidermal surface with spine-like
non-glandular trichome; G. 1 cell secretory head glandular trichome on epidermal
surfaces; H. Venation pattern with 0 (arrow) and 1 (double arrow) veinlet
termination in areole; I. Vein cells on adaxial epidermal surface.
28
A
B
D
C
E
F
G
Fig. 10. S. indica (A-H, X400): A. Spine-like non-glandular trichome on adaxial and
abaxial surfaces; B. Unicellular non-glandular trichome on stem; C. Bicellular nonglandular trichome on midrib, petiole and veins; D. Multicellular non-glandular
trichome on stem (terminal cell shrivelled); E. Multicellular non-glandular trichome
on stem (1 cell shrivelled); F. Multicellular non-glandular trichome on petiole; G.
Multicellular non-glandular trichome on midrib.
29
A
D
G
B
C
E
F
H
I
Fig. 11. S. indica (A-I, X400): A. 2 cells secretory head glandular trichome on
epidermal surfaces; B. Short stalk, 5-7 cells secretory head glandular trichome
(stalk faint, with arrow), on petals; C.-D. Short stalk, 1-2 cells secretory head
glandular trichome on petals and petioles; E. Short (hooked) stalk, 2 cells
secretory head glandular trichome on petals; F. Spherical crystal on abaxial
epidermal surfaces with a stomata with aborted guard cells; G. Small spherical
crystals with short stalk 1 cell secretory head glandular trichome on petal tube; H.
Short stalk, 3 cells secretory head glandular trichome on petals; I. Long stalk, 1
cell secretory head glandular trichome on petal tube.
30
3
2
1
1
3
2
0
1
2
3
0
-10
-10
-20
-20
-30
Similarity
Similarity
-30
-40
-40
-50
-50
-60
-60
-70
-70
-80
1
2
3
4
Fig. 12. Dendrogram of the adaxial
epidermal surface and trichome
characters.
Key:
1
S. cayennensis
2
S. angustifolia
3
S. indica
4
Fig. 13: Dendrogram of the abaxial
epidermal surface and trichome
characters.
Key:
1
S. cayennensis
2
S. angustifolia
3
S. indica
Received:
Revised:
Accepted:
31
nd
March 02 2011
th
November 11 2011
th
November 27 2011